Radio tuning control



Feb. 15, 1938. A, E HED ER 2,108335 RADIO TUNING CONTROL Filed Oct. 21,1956 4 Sheets-Sheet 1- illlllll! W5 dfb-LNVENTOR BY 7 7 77 ATTORNEYSFeb. 15 1938. A HEDGER 2,108,335

RADIO TUNING CONTROL Filed Oct. 21, 1936 4 Sheets-Sheet 2 ammm INVENTORAI TORNEYS Feb. 15, 1938. HEDGER 2,108,335

RADIO TUNING CONTROL Filed 0ot. ,2l, 1936 4 Sheets-Sheet s d J A w ii:

Feb. 15, 1938. HEDGER 2,108,335

RADIO TUNING CONTROL Filed Oct. 21, 1956 4 Sheets-Sheet 4 I f T i i 5?!'lllllll 2T4; ---i 1 Q9 l! I mmumu y W a? VMIZ BY UL 77 ATTORNEYSPatented Feb. 15, 1938 UNITED STATES PATENT OFFICE 14 Claims.

This invention relates to a radio tuning control for actuating thetuning condenser of a radio receiving set.

The principal objects of the invention are: A., to simplify the tuningoperation by enabling the operator to deal with only one wave band at atime, and, B., to provide a machine in which the multiple or decimalsystem is employed so as to enable extreme accuracy of tuning to beobtained, and 0., to enable the operator to manually tune the radio setto the approximately correct position and to then cause the. tuning tobe rendered precisely accurate by providing suitable automatic means toobtain this result. Numerous other objects of the invention andpractical solutions thereof are disclosed in detail in the herein patentspecification whereinz In the accompanying drawings:--- Fig. 1 is afragmentary perspective showing one form of radio receiving set providedwith my improved tuning control.

Fig. 2 is a fragmentary front elevation thereof. Fig. 3 is adisassembled elevation of the four strips of graduated indicators.

Fig. 4 is a vertical, longitudinal section through the receiving set,taken on line 44, Fig. 2.

Fig. 5 is avertical, longitudinal section through I the receiving set,similar to Fig. 4, but showing the parts in a different operativeposition.

Fig. 6 is a horizontal section through the receiving set, taken on line6--6, Fig. 4.

Fig. 7 is a fragmentary, vertical, transverse section through thereceiving set, taken on line 1--'l, Fig. 6. V

Fig. 8 is a fragmentary, vertical, transverse section through thereceiving set, taken on line 88, Fig. 6.

Fig. 9 is a fragmentary, horizontal section through the receiving set,taken on line 9-9, 40 Fig. 8.

Fig. 10 is a fragmentary, vertical, transverse section, showing one ofthe locating plungers and its associated parts, and taken on line l0-l0, Fig. 5.

Similar characters of reference indicate like parts in the severalfigures of the drawings.

When a radio receiving set is to be tuned so as to properly receive theradio waves being sent out from any certain radio sending sta- 50 tion,it is necessary to turn the tuning condenser 28 (Fig. 6) to the properposition. In the present invention this condenser is preferably, thoughnot necessarily, of the straight line type, i. e. the change in KC or MOis 'directly proportional 55 to its movement. The positioning of such atuning condenser is commonly termed the tuning operation, and it is tothis tuning operation that the present invention is exclusively devoted;

This tuning condenser 20 has the usual fixed condenser plates 2| andmovable plates 22 which latter are all connected to a condenser shaft 23which is journaled horizontally and transversely of the radio cabinet 24on bearing standards 25 and 26 suitably secured to the base 29. To saidcondenser shaft 23 are secured primary and secondary,condenser-actuating, gears 21 and 2161, While upon said condenser shaftare journaled tertiary and quaternary, condenser-actuating gears 21b and210.

The primary, condenseractuating gear 21 is small and is adapted to beactuated by a rack 28 having very sharp gear teeth as shown in Fig. 4.This rack is actuated by alongitudinal movement of a rack lever 30, tothe rear end of which it is integrally connected. The secondary,condenser-actuating gear 21a is adapted to be actuated by a secondaryrack 28a which is secured to the rear end of a secondary rack lever 3M.It is to be noted that in the particular embodiment of the inventionherein disclosed the secondary, condenser-actuating gear 21a has adiameter three times the diameter of the primary gear 21, and that,therefore, the secondary rack lever 30a must move longitudinallyrearward 7' three times as far as the primary rack lever 30 to obtainthe same amount of rotation of the condenser shaft 23. In other words,there is a one to three ratio between the primary and secondary racklevers 30 and 30a as regards the effect of their longitudinal movementon the rotation of the condenser shaft 23.

Between the secondary and tertiary rack levers 30a and 3% there is a tento one ratio, and similarly, there is a ten to one ratio between thetertiary and quaternary rack levers 30b and 300. This result is obtainedby suitable gearing, as shown in Figs. 6 and 4 and which is not deemednecessary to be described in detail.

While gears and racks have been illustrated in the present disclosure totransmit power from the rack levers to the condenser 20, it is tobeunderstood that the power may be transmitted through frictional elementsunprovided with teeth but only with ,rolling circle frictional faces.

Each of the four rack levers (for instance, the rack lever 300 shown inFigs. 4, 5, 6 and 8) is fulcrumed on a horizontal, transverse, pivot pin3|. The opposite ends of said pivot pin are provided with spacingsleeves 32 so as to laterally 55 centralize their companion rack leverin its companion slide tube 33. Said slide tubes 33 are suitablysupported on the base 29 on standards 34 and 340. Each slide tube 33 isprovided on its opposite lateral sides with longitudinal guide slots 35which receive the outer ends of their companion pivot pin 3|. Thus, eachrack lever may be moved lengthwise of its companion slide tube 33 androcked in any of its longitudinal positions about its fulcrum pivot pin3| and thus be caused to move its companion rack upwardly intoengagement with its companion condenseractuating gear.

Pivoted at 36 to the front end of each rack lever is a companion,vertical plunger 31. The latter is vertically, slidably arranged in atubular slide head 38 which is longitudinally and slidably arrangedwithin the bore of its companion slide tube 33. Each plunger 31 isnormally maintained in its uppermost position by the weight of itscompanion rack which causes an upward thrust at the front end of itscompanion rack lever, and, consequently, of its companion plunger 31.The upper end of each plunger is provided with a suitable operating knob4|], 40a, 40b and 400 so as to permit its companion plunger to be pusheddown and then removed longitudinally. Each plunger extends upwardlythrough a suitable companion slot 4| formed in the radio cabinet 24, thelatter covering up all of the operating mechanism except the operatingknobs and other similar operating essentials.

Suitably secured to the rear end of each slide head 38 is a flange 43,whose upper end is bent horizontally rearward so as to enable it to besecurely fastened to the lower, front end of a companion flexible strip44, 44a, 44band 440. Each strip is constructed of celluloid or othertransparent, flexible material, and is guided at its rear end betweentwo sheets of felt or similar soft ma terial 45 and 46 so as to enablethe strips to be moved up and down the inclined guide 41 without undueabrasion. A suitable curvilinear directing plate 48 is preferablyprovided so as to cause said strip to feed smoothly into said inclinedguide 41.

Thus, as any certain one of the slide heads 38 is moved forwardly orrearwardly, its companion flexible strip is caused to slide up or downin its inclined guide 41.

Each strip is partially exposed behind a rectangular window 50, 50a, 50band 500 which pierces the inclined front wall 5| of the cabinet 24 andin which is preferably set a small pane of glass 52 inscribed with astraight, horizontal, hair line 53, 53a, 53b and 530. Each of thesestrips (see Fig. 3) is provided with four rows of graduated indicators(54, 54a, 54b, 54c and 55, 55a, 55b, 55c and 56, 56a, 56b, 56c and 51,51a, 51b, 510). These graduated indicators bear numbers which correspondto the wave length of the four following wave bands:-

550 -1500 kc. (550-200 meters) American broadcast 1.50- 4.00 mc. (200-78meters) Aircraft, police signals, etc.

4.00- 10.00 mo. (78-30 meters) Foreign broadcast 10.00- 23.00 mc. (30-13meters) Short wave,

amateur phone, etc.

Each of these strips is adapted to be manually moved lengthwise by itscompanion operating knob until the companion hair line of its companionglass 52 registers with the specific number desired when tuning in anyparticular radio sending station. If, for instance, the operator wishesto tune in the American broadcast station corresponding to 14:80 kc., hefirst pushes the first operating knob 40 downward so as to engage theprimary rack 28 with the primary condenser-actuating gear 21. He thenmoves said knob 40 rearwardly until the numeral 1 of the primary,American-broadcast, graduated indicator 54 appears under the hair line53 of the first window 50, as shown in Fig. 2. This advances the tuningcondenser a certain amount. He then suoces sively moves the three otheroperating knobs 40a, 40b, and 400 until the numerals 4, 8 and 0 appearas shown. Each of these operations advances the tuning condenser afurther amount, the operator allowing each operating knob to rise up,and to thereby disengage its companion rack, before commencing tomanually actuate the next operating knob. This successive movement ofthe different operating knobs operates to successively advance thetuning condenser 25 until it is finally brought to a correct positionfor receiving radio signals from the particular station desired which inthis case was assumed to be stationv 1480 kc. on the American-broadcastband.

It is to be noted that the ratio between the movement of the firstoperating knob 40 and the corresponding movement of the tuning condenser20 is relatively high. In other words, the ratio of the primarycondenser actuating means is high and the condenser rotated aconsiderable amount for a small movement of the primary operating knob40. The ratios of the succeeding condenser-actuating means aresuccessively lower. In the particular embodiment of the invention heredisclosed, the ratio between the primary and secondarycondenser-actuating means is three to one. concomitantly, the physicaldimension of a unit distance on the primary, American-broadcast,graduated indicator 54 of the first flexible strip 44 is three times asgreat as the physical dimension of a unit distance on the secondary,American-broadcast, graduated indicator 54a of the secondstrip 44a. Thismeans that the cor-- responding gear ratios are such that the secondoperating knob 40a must be moved three times as far as the firstoperating knob 40 to effect the same movement of the tuning condenser20.

Each of the succeeding operating knobs 40b and 400 and their racks 28band 28c must be moved ten times as far as its predecessor to obtain alike amount of condenser movement. This means, of course, that thecondenser can be very accurately moved to any desired station in amanner similar to that employed in the construction r of an ordinaryshop micrometer in which a large. coarse movement of the knurledoperating sleeve causes an extremely fine and accurate movement of thesliding head of the micrometer.

It is to be noted that the numbers on the first strip 44 do not all goup to 9, this being due to the idiosyncrasies of the various broadcastbands, plus the fact that it is desirable to have the smallest unitdimensions sufficiently large to be easily located on their companionhair lines. In the second strip 44a, however, all of the numbers go upto 9, and hence this may be termed a strip constructed on the decimalsystem. The numeral 10 has been omitted in each graduated indicatorbecause it might easily cause confusion and because it is unnecessary,being the equivalent of 1 in the next graduated indicator of the samewave band set of graduated indicators. Similarly, the last two strips44b and 440 are decimal strips and, obviously, the ratios between thecondenser-actuating means of the second and third and the third andfourth strips are necessarily equal to ten. Because of this fact thelast three strips 44a, 44b and Me are identical in appearance, althoughdifferent in function. f

V In an ordinary radio receiving set the zero position is at the 550 kc.American-broadcast station, there being no need to move the condenser tothe zero kc. position. This is, of course, because there are no stationswhich send out radio waves of less than 550 kc. In the present system,which is based upon a multiple or pseudo-decimal system, it is desirablethat the set be so arranged thatit can be indexed, theoretically atleast to receive waves of zero kc. This is because of the inherentqualities of a decimal system of condenser actuation. Hence, thec-ondenser of the present invention may be said to be at its zeroposition (similar to the zero of an ordinary radio set) when the tuningcontrol is set for 55!) kc. on the American-broadcast band. From this itfollows that, when the tuning control disclosed in the present inventionis set at zero kc., the condenser position is negative. Thischaracteristic of the present invention is not advanced as a point ofsuperiority of the present invention, as far as the operation thereof isconcerned, but merely as a fundamental feature which must beincorporated in such a radio tuning control if the tuning control is tobe based on the multiple systern and be as simple and rational as thathere disclosed.

It is to be understood that the one condenser 20 is used for all fourwave bands, although, of course, for each wave band a differentelectrical circuit is required. Consequently, the tuning of the radioset for any of the other three wave bands is similar to that justdescribed, except that difierent graduated indicators are required onthe four strips for each of the other three wave bands. For instance, ifthe operator desires to tune the radio receiving set to station 3.125me. on the aircraft wave band he first pushes down the first operatingknob 40 and pushes the same .rearwardly '(with said knob remainingdepressed) until the numeralB appears on the primary, aircraft-band,graduated' indicator 55 of the first strip 44 under the hair line 53 ofthe first window 50. He then releases said first operating knob 40,thereby disengaging the primary rack 28 from the primary,condenser-actuating gear 21. He then seizes the second operating knob40a and depresses it and pushes it rearwardly (with said knob 40aremaining depressed) until the numeral l appears on the secondary,aircraft-band, graduated indicator 55a of the second strip 44a under thehair line 53a, of the second window 50a. He

then releases said second operator knob 40a and successively actuatesthe third and fourth operating knobs flilb and 400 until the numerals 2and 5 of the tertiary and quaternary, aircraftband, indicator strips552) and 55c'appear under the hair lines 53b and 530.

The operation of tuning in a station on the foreign-broadcast band1.00-10.00 me.) or on cators may be used for all the four wave bands.For instance, the graduated indicators 5%, 55b, 56c and 510 may be used,solely for all wave bands, i. e., without any other graduatedindicators, to take care of the other three wave bands,

In such case, each of the strips 44, 44a, 44b and 440 would contain onlythe one graduated indicator, and, if desired, these four strips may beconstructed identically in form and size. In such case, of course, thegear ratios between each condenser-actuating means would have a ten toone ratio with its adjacent or neighbor condenseractuating means. It isto be acknowledged that such a refinement of the invention is not easyof accomplishment in that it requires much out and try work and that ithas not been effected in actual practice, but is deemed, nevertheless,to be a logicalcarrying out of the spirit of the present invention.

To enable the present invention to be tuned to any desired one of thefour wave bands, it is necessary to provide a suitable electric circuitfor each band, and to control the selectivity of the circuits by asuitable wave switch which operates in the usual and well known mannernot deemed necessary to be described here. This switch is actuated by asuitable wave-switch handle 60. The latter has four operative positionscorresponding to the four wave bands, and is arranged at the front endof a horizontal, longitudinal wave-switch shaft 6! (see Fig. 4) which issuitably journaled at 62 in the base 29 of the radio receiving set.Secured to an intermediate part of said wave-switch shaft 6i is a pinion53 which meshes with a horizontal, transverse rack 64 (see Figs. 8 and4) formed integrally in the lower part of a vertical, transverse shutterplate 65. The latter is slidably arranged on the base 29 in suitableslides 66 so as to be able to move horizontally and transversely ofsaid'base. Formed in said shutter plate 65 is a rectangular, indicatoraperture 61 in which is fitted a window spanned by some such transparentmaterial as celluloid or Cellophane having four panes each of which hasa different color, for instance pane i is white, 70a is green, liib isviolet, and 100 is red. The colors of these window panes correspond tothe colors of the four sets of graduated indicators of the strips 44,44a, 44b and Mic as indicated. The one or other of these four coloredpanes is adapted to be registered with the orifice E of a waveband,indicating lens II which is set into the inclined front face 55 of theradio receiving cabinet 24 andreceives its illumination from a suitableelectric lamp bulb '12 secured to'a bracket 13 mounted on the base 29 ofthe set. Thus, as the wave switch handle 60 is turned to any one of itszontal row of four, narrow, rectangular slits M,

Ma, 14b and MC. The width of each of these slits is the same as thewidth of each of the graduated indicators, and the location of each inthe shutter plate is such that when any certain one of the colored panesH1, ma, b or 'Hic of the shutter aperture El is in register with theindicating lens H, said rectangular slits are all in register with thegraduated indicators of one par ticular Wave band. For instance, in Fig.8 the white pane iii of the rectangular aperture Bl is in register withthe orifice E5 of the lens H, and

the slits M, Ma, Mb and Me are in register with the American-broadcast,graduated indicators 54, 54a, 54b and 540. This arrangement acts notonly as a telltale to notify the operator as to just what wave band isready for tuning, but goes further and actually prevents him from seeingany other graduated indicators except those associated with theparticular wave band he is dealing with. This result is effected byreason of the fact that the flexible strips 44, 44a, 44b and 440 areadapted to be illuminated through their companion windows 50, 50a, 50band 500 from companion electric light bulbs 19, 19a, 19b and 190 (seeFig. 9), but the slits 14, Ma, 14b and 140 only allow the light fromthese four bulbs to pass through the graduated-indicators of one singlewave band set of graduated indicators at a time. To carry out thisscheme consistently, the different wave-band, graduated indicators ofthe flexible strips 44, 44a, 44b and 440 are differently colored tocorrespond with the colored panes i9, Illa, 10b and 100 of the indicatoraperture 61. Thus, for any certain position of the wave switch handle60, the same color is emanated from the indicator lens H as appears inthe windows 58, 50a, 50b and 5510. This renders the receiving set morefoolproof in operation because, after it has been used for some time,the operator learns and automatically associates a certain wave bandwith a certain color which identifies it.

It is highly desirable in an apparatus of this character that eachsuccessive step of operations be very accurately performed. It is alsohighly desirable that no more dependence be placed upon the operatorthan is absolutely essential. In the present invention provision is madewhereby the operator, in carrying out each operative step, is merelyrequired to effect each successive tuning operation with a moderatedegree of accuracy, the device itself causing the tuning to be accuratewithin extremely small limits. This result is obtained not only by theuse of the pseudo-decimal system previously described, but,additionally, by a special form of the plungers 31. The intermediatepart of each plunger is provided with a laterally extending lug (seeFig. 10) whose upper edge is formed to provide a knife edge 16. Thisknife edge is adapted to enter into one or other of a plurality oflocating notches 11 formed in its companion slide tube 33, said notchesbeing formed in the one (left) face of the slot 18 which extends alongthe upper longitudinal face of each slide tube 33 to permit of thelongitudinal movement of its companion plunger 31. Thus, if the operatorfails to properly longitudinally position any certain plunger 3'1, theupper knife edge 16 thereof will automatically shift said plunger andits companion slide head 38 longitudinally a small but sufficient amountto eifect an accurate positioning of said slide head, and, consequently,of the tuning condenser 20 to which it is operatively connected. It isto be understood that this centralizing operation is completely effectedby any certain plunger 31 before its companion rack is disengaged fromits companion condenser-actuating gear 21, 21a, 211) or 210. ,It is alsothought to be obvious that a suitable spring may be employed to pusheach plunger vertically upward if the herein disclosed employment ofunbalanced gravitational forces proves too slow or otherwise notentirely satisfactory.

It is desirable that no electric current be sent to the loud speaker ofthe radio receiving set while the tuning operation is in progress. T0attain this result the present invention provides a cutout switch 80 atthe lower end of each plunger 31. The four switches at the lower end ofthe four plungers 31 are in series with each other and are thus arrangedin the electrical system in such manner that, if any one switch is open,no current will flow to the loud speaker. This result is obtained in theusual and well known manner and is thought to warrant no further commenthere.

It is also deemed desirable to have means provided whereby, when theradio is being tuned, only one rack at a time can be engaged with itscompanion condenser-actuating gear, and, when the radio is not beingtuned, that none of the racks can be engaged with their companioncondenser-actuating gears. This result is obtained by the use of a stopbar Bl which is disposed horizontally and transversely of the machineand is transversely slidable in a pair of brackets 82, 83 secured to thebase 29. This stop bar is provided on its lower face with a singlerectangular notch 84 which is adapted to either register with anydesired one of the rack levers 30, 30a, 30b and 300, or to be movedtransversely to the extreme limit of its motion to the right (as in Fig.l) in which latter case said notch is out of register with all of saidrack levers.

The lateral shifting of said stop bar is effected manually by a safetyknob 85 which is preferably pointed at its rear end, as shown, to enableits position to be accurately gauged. Said safety knob is secured to theupper end of a safety post 86 which extends through a horizontal,transverse slot 81 formed in the cabinet 24 of the radio receiving setto permit transverse movement of said safety post. The lower end of saidsafety post 86 is secured to a horizontal, transverse slide rod 88 whichis slidably mounted on the base 29 in a slide tube 90 which is securedat its opposite ends to the base 29 in brackets SI, 92, said slide tube90 being slotted on its upper face at 93 to permit the safety post 86 tomove horizontally and transversely of the radio set, together with theslide rod 88 to which it is connected. The opposite ends of said sliderod 88 are bent horizontally rearward, as shown in Fig. 6, and aresuitably secured at their rear ends to the opposite ends of the stop bar8i.

Said pointed safety knob 85 is in the same ver tical, longitudinal planeas the notch 84 of the stop bar 8! so that the operator can easily tellby the position ofsaid knob what the position of said notch is. Thisalignment operation is facilitated by the position of the fourhorizontal, longitudinal slots 4| which pierce the radio cabinet topermit longitudinal movement of the plungers 31.

Operation We will first assume that the operator wishes to tune in theradio receiving set to station 1480 kc. on the American-broadcast radioband. He first turns the wave switch handle 60 until a white lightflashes through wave-band indicating lens II. This operationsimultaneously brings the four rectangular slits 14, 14a, 14b and of theshutter plate 65 into register with the American-broadcast, graduatedindicators 54, 54a, 54b and 540, and thereby causes the latter to beilluminated from their companion lights 19, 19a, 19b and with a whitecolor inasmuch as the color of these particular graduated indicators iswhite. All of the other graduated indicators are at this time totallyinvisible because they are so constructed as to only be visible whenlight is passed through them but not when light is reflected from theirfront surfaces.

The operator now moves the safety knob 85 laterally until it registerswith the slot 4| of the primary operating knob .40. This causes thenotch .84 of the stop bar 8 to register with the primary rack lever 30and permits the rear end of the latter to be elevated. The operator nowgrasps the primary operating knob 40 and pushes it downwardly. Thisopens its companion cutout switch 80 and thereby disconnects the loudspeaker while this particular tuning operation is in progress. Thismovement also lifts the rear end of the primary rack lever .30 so as tocause the sharp pointed teeth of the rack 28 thereof to mesh with thesharp pointed teeth of the primary condenser-actuating gear 21. Theoperator now (with saidoperating' knob 40 still depressed) moves saidprimary operating knob rearwardly, until the numeral I of the primary,American-broadcast, graduated indicator 54 registers with the hairline53 of window 150,, Th s causes the tuningcondenser to be rotated anamount corresponding to themovement of said primary operating'knob 4ll.The operator now releases said primary operating knob 40, and therebyallows its knife edge 16 to accurately engage with the adjacent locatingnotch '11 of its companion slide tube 33. Thiscauses the tuningcondenser to be very accurately located, as far as this initial tuningstep is concerned, even though the'operator does not move theprimaryoperating knob to precisely the position in tended, said knife edge 16causing a slight longitudinal shifting of its companion rack lever inthe event that the latter has been longitudinally positioned in anapproximately correct but not an exactly correctposition- The operatornow shifts the safety knob 85 to the right so as to position the same inregister with the secondaryoperating knob 40a. He then pushes the latterdown and moves it rearwardly until the numeral 4 of the secondary,Americanbroadcast, graduated indicator 54a is in line with the hair line53a. This process is carried out in a similar fashion so as to positionthe numerals 8 and 0 of the tertiary and quaternary, Americanbroadcast,graduated indicators 54b and 540 under the hair lines 5312 and. see; Ifthe operator desires that this tuning position be not accidentallyaltered, he moves the safety knob 85 .to its extreme right position, asshown in Fig. 1, there by preventing any manipulation of anyof theoperating knobs 46, 40a, 4021 or 400.

The operator now regulates the volume control switch 94 and thesensitivity switch. 95 in the usual and well known manner.

We will now assume that the operator wishes to tune in station 3.125 me.on the aircraft-wave band. He first turns the wave-switch handle 60until a green light is seen through the waveband, indicating lens 7|.This operation simultaneously illuminates all of the aircraft-band,graduated indicators 55, 55a, 55b and 55c which are colored green tomatch the light coming through the indicating lens H. The rest of thegraduated indicators are at this time invisible. The operator now movesthe safety knob 85 over to its extreme left position in line with theslot All of the primary operating knob 49. He then push-es down thelatter and moves it longitudinally until It is to be noted that when theoperator shifted from station 1480 kc. on the American-broadcast band tostation 3.125 me. on the'aircraftband,

he did not have to return the radio receiving set to its zeropositionb'ut' merely shifted eachof V the operating knobs in turn to itsnew position,

Thisoperation, incidently, he can effect by moving said operating knobsin any order he may desire.

, I claim as my i,nvention:

1. A radio tuning control associated with the tuning condenser of aradio receiving set and comprising: a pair of graduated indicatorshaving their graduations of different length and normally disconnectedfrom the condenser; and a pair of condenser actuating means of differenttransmitting ratio, each of said means being adapted to connect itscompanion indicator with the condenser,

'2. A radio tuning control associated with the tuning condenser of aradio receiving set and comprising: a pair of graduated indicatorshaving their graduations of different length and normally disconnectedfrom the condenser; and a pair of condenser actuating means 'ofdifferent transmitting ratio, each of said means being adapted toconnect its companion indicator with the condenser, the arrangementbeing such that when the indicators are both set at zero the condense isin a negative position.

3. A radio tuning control associated with the tuning condenser of aradio receiving set and comprising: a pair of graduated indicatorshaving theirgraduations of different length and normally disconnectedfrom the condenser; and a pair of condenser actuating means of diiferenttransmitting ratio, each of said means being adapted to connect itscompanion indicator with the condenser, the arrangement being such thatwhen the indicators are both set at zero the condenser is in a negativeposition and, when the indicators are; set for the lowest station inany. certain wave band, the condenser is in its zero position.

4. A radio tuning control associated with the tuning condenser of aradio receivingset and comprising; a pair of indicators normallydisconnected from the condenser, each indicator having a plurality ofgraduations and the corresponding graduations of the indicatorsrelatively to each other having the same ratio; and a pair of condenseractuating means of different ratio, each of said means being adapted toconnect its oompanion indicator with the condenser.

5. A radio tuning control associated with the tuning condenser of aradio receiving set and comprising: a pair of indicators normallydisconnected from the condenser, each indicator having a plurality ofgraduations and the corresponding graduations of the indicatorsrelatively to each other having the same ratio; a pair of condenseractuating means of different ratio, each of said means being adapted toconnect its companion indicator with the condenser; and means forilluminating the one or other set of graduations on the indicators.

6. A radio tuning control associated with the tuning condenser of aradio receiving set and comprising: a pair of indicators normallydisconnected from the condenser, each indicator having a plurality ofgraduations and the corresponding graduations of the indicatorsrelatively to each other having the same ratio; a pair of condenseractuating means of different ratio, each of said means being adapted toconnect its companion indicator with the condenser; and means forilluminating the one or other set of graduations on the indicatorsconsisting of a plate having a pair of apertures and adapted to be movedso as to have said apertures register with the one or other set ofgraduations.

'7. A radio tuning control associated with the tuning condenser of aradio receiving set and comprising: a pair of indicators normallydisconnected from the condenser, each indicator having a plurality ofgraduations and the corresponding graduations of the indicatorsrelatively to each other having the same ratio; a pair of condenseractuating means of different ratio, each of said means being adapted toconnect its companion indicator with the condenser; a wave switch; andmeans for co-relating the position of said switch with one or other setof graduations on the indicators.

8. A radio tuning control associated with the tuning con-denser of aradio receiving set and comprising: a pair of indicators normallydisconnected from the condenser, each indicator having a plurality ofgraduations and the corresponding graduations of the indicatorsrelatively to each other having the same ratio; a pair of condenseractuating means of different ratio, each of said means being adapted toconnect its companion indicator with the condenser; a wave switch; and awave light, the color of the illumi nation from which is controlled bysaid wave switch and is co-related with the sets of graduations on theindicators.

9. A radio tuning control associated with the tuning condenser of aradio receiving set and comprising: a pair of indicators normallydisconnected from the condenser, each indicator having a plurality ofgraduations and the corresponding graduations of the indicatorsrelatively to each other having the same ratio; a pair of condenseractuating means of different ratio, each of said means being adapted toconnect its companion indicator with the condenser; a wave switch; awave light; and means for illuminating the one or other set ofgraduations on the indicators and simultaneously controlling the colorof the illumination emanating from said wave light, consisting of aplate adapted to be moved by said wave switch and having a pair ofapertures adapted to register with the one or other set of graduationsand having a pair of colored members, the one or other of which isadapted to register with the wave light.

10. A radio tuning control associated with the tuning condenser of aradio receiving set and comprising: a pair of graduated indicatorshaving their graduations of different length and normally disconnectedfrom the condenser; a pair of condenser actuating means of differenttransmittin-g ratio, each of said means being adapted to connect itscompanion indicator with the condenser; and means for shifting eachcondenser actuating means to one or other exact location when saidactuating means is shifted to approximately the correct position.

11. A radio tuning control associated With the tuning condenser of aradio receiving set and comprising: a pair of graduated indicatorshaving their graduations of different length and normally disconnectedfrom the condenser; a pair of condenser actuating means of difierenttransmitting ratio, each of said means being adapted to connect itscompanion indicator with the condenser; a precision member having aplurality of V-shaped notches corresponding with the graduations of saidindicators; and a pointed plunger adapted to engage with the one orother of said notches and to be longitudinally movably connected withone of said condenser actuating means.

12. A radio tuning control associated with the tuning condenser of aradio receiving set and comprising: a pair of graduated indicatorshaving their graduations of difierent length and normally disconnectedfrom the condenser; a pair of condenser actuating means of difierenttransmitting ratio, each of said means being adapted to connect itscompanion indicator with the condenser; and means'for preventing morethan one of said condenser actuating means being actuated at a time.

13. A radio tuning control associated with the tuning condenser of aradio receiving set and comprising: a pair of graduated indicatorshaving their graduations of difierent length and normally disconnectedfrom the condenser; a pair of condenser actuating means of diiTerenttransmitting ratio, each of said means being adapted to connect itscompanion indicator with the condenser; and means for preventing morethan one of said condenser actuating means being actuated at a time andfor preventing all of said actuating means being actuated when the radiotuning operation has been completed.

14. A radio tuning control associated with the tuning condenser of aradio receiving set and comprising: a pair of graduated indicatorshaving their graduations of different length and normally disconnectedfrom the condenser; a pair of condenser actuating means of differenttransmitting ratio, each of said means being adapted to connect itscompanion indicator with the condenser; and a cutout switch in serieswith the electrical system of the radio set and adapted to be openedwhenever any one of the condenser actuating means is being actuated.

ALBERT E. HEDGER.

